Scots bid to stop Naples becoming next Pompeii

Published on 04/05/2003 01:00

IT IS one of the world’s most violent and dangerously unpredictable killers with thousands of victims to its name.

Mount Vesuvius is the famous volcano that buried the Roman city of Pompeii and its inhabitants under a blanket of searing hot ash in AD 79, and which has erupted more than 50 times since.

Now Italian volcanologists believe Vesuvius could erupt at any time and have turned to a Scottish scientist to help them predict an explosion that could place at risk up to two million people living in its shadow.

Physicist Hugh MacKenzie has been called in by the Italian authorities because the technology he has developed promises to warn of an eruption weeks ahead rather than hours or days. And that could save lives.

The new system detects tell-tale traces of a certain form of carbon dioxide which seeps from the ground in increasing quantities as magma approaches the Earth’s surface.

Mackenzie, a senior lecturer at Heriot-Watt University in Edinburgh, will start setting up gas monitoring stations around the volcano this summer.

"Vesuvius has proved how destructive it can be many times throughout history, yet more people live close to it now than ever before," MacKenzie said.

"Basically, the large city of Naples is very close to Vesuvius, and is hoping that history will not repeat itself. But as Vesuvius has a habit of erupting around every 60 years and last blew in 1944, the view is that it could so again in the near future.

"So the Italian government is understandably keen to deploy as many weapons in its battle against the forces of nature as it can. The hope is that our technique will act as a very early warning system that can sound the alert before there are any clear physical signs of an impending eruption."

The system is based on the principle of photoacoustics, first reported by Alexander Graham Bell, the inventor of the telephone, in 1880.

When light is shone into a photoacoustic cell containing a gas, the heat produced sets off a tiny thermal "explosion" that can be picked up by sensitive microphones. Different gases produce their own tell-tale soundwave.

Prior to any volcanic eruption, magma wells up through the earth’s crust via any weaknesses in the rock structure. As it does so, it releases a certain form of trapped carbon dioxide gas, known as 13CO2, that makes its way to the surface and seeps out in a wide area around a volcano’s base.

There is an array of other modern techniques, such as seismic monitoring, for detecting physical signs of an imminent eruption. But a photoacoustic cell capable of detecting fast-rising levels of 13CO2 should be able to provide an indication well in advance that a surface eruption is possible.

"Given that using a collage of modern techniques it is only possible to give one day’s accurate warning before an eruption, it is absolutely imperative that improvements are made to the detection and interpretation of signs and events that could give advance warning of an increase in volcanic activity," MacKenzie said.

The technique has been successfully tested in the fields around Mount Etna in Sicily, which erupted spectacularly last year as part of a huge increase in volcanic activity in Italy.

Last October, Etna treated observers to Europe’s biggest explosive eruption in centuries, knocking down a ski lift and engulfing a ski lodge in hot lava. In December, 32 people were injured when an oil tank exploded beneath the lava.

To the north, the tiny tourist island of Stromboli was evacuated in January after 10 million cubic metres of volcanic rock and boiling lava slithered into the Mediterranean. The eruption produced a cloud of steam and ash that wreathed the 3,000ft Stromboli mountain and a tidal wave that rocked ships in ports more than 100 miles away.

The geological fault lines underlying the eruptions stretch to the Italian mainland. Five days after Etna exploded in October, an earthquake, measuring 5.4 on the Richter scale, struck the south-eastern Molise region killing 26 children in a hill village school.

As volcanologists suspect the faultlines connect up with the Vesuvius system to the north, the chances of an eruption appear to be increasing. Concern is high as Vesuvius is the most-heavily populated volcano in the world.

"There is a significant increase in volcanic activity in the Italian system at the moment and there is an anxiety that these geological changes will affect Vesuvius," MacKenzie said. "I imagine the tension in Scotland would be rising similarly if we suspected that Arthur’s Seat was about to blow."

MacKenzie, whose work is being funded by the government-run Institute of Geology and Volcanology in Naples, hopes that photoacoustic techniques will eventually be used to help predict volcanic eruptions around the world. There are currently about 600 active volcanos spread across the globe.

He added: "There are refinements to be made, but what pleases me is that here we are in Scotland without any volcanic worries, but still with a role to play in tackling this very serious problem."